linux-kernel - Re: regulator: deadlock vs memory reclaim

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Message-ID: <20200810201846.GA12091@qmqm.qmqm.pl>
Date:   Mon, 10 Aug 2020 22:18:46 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: regulator: deadlock vs memory reclaim

On Mon, Aug 10, 2020 at 11:15:28PM +0300, Dmitry Osipenko wrote:
> 10.08.2020 23:09, Michał Mirosław пишет:
> > At first I also thought so, but there's more. Below is a lockdep
> > complaint with your patch applied. I did a similar patch and then two more
> > (following) and that is still not enough (sysfs/debugfs do allocations,
> > too).
> Then it should be good to move the locking for init_coupling() like I
> suggested and use GFP_NOWAIT for the two other cases. It all could be a
> single small patch. Could you please check whether GFP_NOWAIT helps?

This would be equivalent to my patches. Problem with sysfs and debugfs
remains as they don't have the option of GFP_NOWAIT. This needs to be
moved outside of the locks.

Best Regards,
Michał Mirosław